This research will examine iron metabolism in cultured rat heart muscle cells, using cells both in "normal" conditions and in the "iron-overloaded" state. Specific goals are as follows: 1) To define the mechanism(s) of iron uptake and the routes of intracellular iron movement in the cells. 2) To determine some of the physiological consequences of iron-overload by monitoring the effects of excess iron on growth, ultrastructure, and the activities of key enzymes. 3) To attempt rescue of iron-toxic cells with iron chelating agents which may become useful in therapy of human iron overload diseases. This research will contribute new information related to normal human iron metabolism and may yield a better understanding of the pathology of iron overload, as well as suggest clues for more effective treatment of iron overload diseases.